After Steinbrück graduated from high school in 1968, he completed 18 months of compulsory military service. He elected to extend his enlistment by six months, and in 1969, while still in the military, he joined the SPD. From 1970 to 1974 he studied economics and social sciences at the University of Kiel, and he graduated with a degree in economics in December 1974. In January 1975 he relocated to Bonn, the provisional capital of West Germany. Aside from a short stint with West Germany’s permanent diplomatic mission in East Berlin in 1981, Steinbrück would remain in Bonn for a decade. There he worked for several ministries, the Federal Chancellery, and, after the formation of the Christian Democratic Union (CDU) government under Helmut Kohl in 1982, for the parliamentary group of the SPD in the German Bundestag.

In 1985 he began working for the government of North Rhine–Westphalia, Germany’s most populous state, and the following year he became director of the office of the state’s premier, Johannes Rau. Steinbrück returned to Kiel in 1990 and, after years of working for politicians, started his own political career. He served as secretary of state for the Environment Ministry of Schleswig-Holstein (1990–92) before moving to the Ministry of Economic Affairs, Technology, and Transportation (1992–93). He was elevated to minister of economic affairs for Schleswig-Holstein in May 1993 and served in this role until October 1998, when he accepted a position with a similar portfolio for the government of North Rhine–Westphalia. Steinbrück was named finance minister for North Rhine–Westphalia in 2000, and he became premier of that state in November 2002.

In May 2005 the SPD in North Rhine–Westphalia, led by Steinbrück, lost in state elections in historic fashion; for the first time in 39 years, the SPD would not head the government. This result was seen as a reaction to Chancellor Gerhard Schröder’s reform of the welfare system at the federal level, however, so the loss was not blamed on Steinbrück, who was elected deputy chairman of the SPD in November 2005. That same month he was appointed finance minister in the cabinet of Angela Merkel’s grand coalition government. The fit was a good one, as Steinbrück belonged to the more business-friendly right wing of his party, and he was regarded as a skilled administrator even by his political opponents. His goal of presenting a balanced budget for the first time in decades fell victim to the global financial crisis that began in 2008. Still, his role during the financial crisis was generally seen as positive. He and Merkel appeared as calming crisis managers, most noticeably when the pair faced cameras together on October 5, 2008, to reassure the Germans that their savings deposits were safe.

The 2009 parliamentary election saw the demise of the grand coalition and the end of Steinbrück’s tenure as finance minister. He was elected to the Bundestag without a leadership position in the government or his party, but he continued to rank among the most popular politicians in Germany. In 2010 he published his first book, Unterm Strich (“The Bottom Line Is”), which detailed his views on the financial crisis and Germany’s position in the future. He followed in 2011 with Zug um Zug (“Move by Move”), a collection of conversations with former chancellor Helmut Schmidt. Both books were best sellers, and it was Schmidt who promoted Steinbrück as a possible candidate for chancellor in the 2013 election. In December 2012 Steinbrück was elected by his party to lead the SPD in the September 2013 general election, in which it captured about 25.7 percent of the vote to finish second to the CDU-CSU alliance (which took about 41.5 percent). Because the alliance’s previous partner in its governing coalition, the Free Democratic Party, failed to reach the threshold necessary for representation in the Bundestag, the SPD joined Merkel’s new government, but without Steinbrück in a leading role. He withdrew from the leadership ranks of his party but continued to serve as a member of the Bundestag.